The European Union recently took the lead in this effort, imposing an oil embargo against Yugoslavia, NATO officials said. Oil is considered a "war material," prohibited under U.N. resolutions.

President Clinton told reporters here April 24 that it doesn't make sense for allied pilots to risk their lives nightly to deplete Yugoslavia's oil reserves while new supplies arrive in other ways. "If we want this campaign to succeed -- with economic and political pressure and air action -- then we have to take every reasonable means to give it a chance to succeed," he said.

NATO officials have received reports of Serb forces in Kosovo siphoning gas from abandoned refugees' cars, said NATO spokesman Jamie Shea. "That does show that this is now becoming serious and that encourages us to persevere in denying Milosevic any access to refined oil."

Naval interdiction would most likely involve adding more NATO ships to those already in the region, a NATO spokesman said. At present, about 20 NATO warships, including the aircraft carrier USS Theodore Roosevelt and its battle group, are involved in Operation Allied Force.

The move toward naval interdiction was announced during NATO's 50th anniversary summit here April 23 to 25. Throughout the historic meeting, NATO leaders persistently expressed the will to not only continue the allied air campaign, but to intensify efforts to degrade Milosevic's military capabilities.

The allies stuck to their position that air strikes would ultimately accomplish NATO's goals and that ground troops would not be deployed until a peace agreement was reached and a permissive environment was secured. Then and only then, NATO plans to deploy a security force to ensure the safe return of ethnic Albanian refugees to their homes in Kosovo.

NATO leaders repeatedly expressed solidarity and resolve, said National Security Adviser Sandy Berger. "If there was one refrain that was heard again and again and again," he said, "it was this: This alliance stands solidly behind the air campaign. It will intensify that campaign and it will prevail."

Addressing reporters April 23 at the Ronald Reagan International Trade Center, Berger reported that NATO officials are determined to "extract a higher and higher price" from Milosevic until the Yugoslav dictator decides to cut his losses."

"Our position remains the same," Berger said. "No. 1, we are committed to this air war. No. 2, we believe it can and will succeed. No. 3, I'm more convinced of this today because I've seen 19 leaders who have made it very clear that they will succeed."

NATO has approved plans to further augment allied air forces. About 300 more aircraft, mainly American, are soon to take part. Clark also plans to add more refueling tankers to allow intense air strikes to be conducted 24 hours a day. Plans also call for adding more reconnaissance aircraft to gather battle damage intelligence and keep track of the humanitarian situation.

From March 30 to April 23, NATO delivered 11,120 tons of aid, fed and sheltered 85,000 refugees and supplied 729 tons of medicine, German air force Col. Konrad Freitag told reporters. The Supreme Headquarters Allied Powers Europe spokesman said NATO flights in the 24 hours before the summit opening delivered nine tons of food and four tons of medicine to Albania and eight tons of medical supplies to the Former Yugoslav Republic of Macedonia.